C++/STL Algorithms Modifying sequence operations/reverse
Содержание
- 1 Reverse a sequence
- 2 Reverse the order of the found element with value 3 and all following elements
- 3 Sort and reverse an int array
- 4 Use reverse to reverse order from second to last element but one
- 5 Use reverse to reverse the order of elements
- 6 Using the STL generic reverse algorithm with a vector
Reverse a sequence
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
void show(const char *msg, vector<int> vect);
int main()
{
vector<int> v;
for(int i=0; i<10; i++) v.push_back(i);
show("Original order: ", v);
reverse(v.begin(), v.end());
show("After reversal: ", v);
return 0;
}
void show(const char *msg, vector<int> vect) {
cout << msg << endl;
for(unsigned i=0; i < vect.size(); ++i)
cout << vect[i] << endl;
}
Reverse the order of the found element with value 3 and all following elements
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main()
{
vector<int> coll;
vector<int>::iterator pos;
// insert elements from 1 to 6 in arbitrary order
coll.push_back(2);
coll.push_back(5);
coll.push_back(4);
coll.push_back(1);
coll.push_back(6);
coll.push_back(3);
// find the first element with value 3
pos = find (coll.begin(), coll.end(), // range
3); // value
// reverse the order of the found element with value 3 and all following elements
reverse (pos, coll.end());
// print all elements
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
cout << *pos << " ";
}
cout << endl;
}
/*
2 5 4 1 6 3
*/
Sort and reverse an int array
#include <algorithm>
#include <iostream>
#include <iterator>
using namespace std;
int main( )
{
const int num_costs = 4;
const float cost[num_costs] = { 4.77, 6.99, 8.88, 9.22 };
copy( cost, cost + num_costs,ostream_iterator<float>( cout, " " ) );
const char* fruit[] = { "A", "B", "C" };
copy( fruit, fruit + sizeof( fruit ) / sizeof( fruit[0] ),
ostream_iterator<const char*>( cout, " " ) );
int year[] = { 2001, 2002, 2003, 2004, 2005 };
const int num_years = sizeof( year ) / sizeof( year[0] );
copy( year, year + num_years,ostream_iterator<int>( cout, " " ) );
sort( year, year + num_years );
copy( year, year + num_years,ostream_iterator<int>( cout, " " ) );
reverse( year, year + num_years );
copy( year, year + num_years,ostream_iterator<int>( cout, " " ) );
}
Use reverse to reverse order from second to last element but one
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
using namespace std;
int main()
{
vector<int> coll;
INSERT_ELEMENTS(coll,1,9);
PRINT_ELEMENTS(coll,"coll: ");
// reverse order from second to last element but one
reverse (coll.begin()+1, coll.end()-1);
PRINT_ELEMENTS(coll,"coll: ");
}
/*
coll: 1 2 3 4 5 6 7 8 9
coll: 1 8 7 6 5 4 3 2 9
*/
Use reverse to reverse the order of elements
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
using namespace std;
int main()
{
vector<int> coll;
INSERT_ELEMENTS(coll,1,9);
PRINT_ELEMENTS(coll,"coll: ");
// reverse order of elements
reverse (coll.begin(), coll.end());
PRINT_ELEMENTS(coll,"coll: ");
}
/*
coll: 1 2 3 4 5 6 7 8 9
coll: 9 8 7 6 5 4 3 2 1
*/
Using the STL generic reverse algorithm with a vector
#include <iostream>
#include <vector>
#include <cassert>
#include <algorithm> // For reverse
using namespace std;
template <typename Container>
Container make(const char s[])
{
return Container(&s[0], &s[strlen(s)]);
}
int main()
{
vector<char> vector1 = make< vector<char> >("abc");
reverse(vector1.begin(), vector1.end());
assert (vector1 == make< vector<char> >("cba"));
return 0;
}